It has been widely forecast that fabrication technology for computer chips will reach its limits in about a decade. The dramatic impact that this will have on almost every aspect of technological advance has motivated massive research efforts in industry, academia, and national laboratories to develop the replacement or extension strategy. The objective is to be able to make nanometer sized circuit elements, assemble them into complex circuits, integrate them with current semiconductor device technology, and maintain costs within acceptable limits. To this end, individual nanometer sized elements have been synthesized and shown to be electrically active. These include carbon nanotubes, oxide nanotubes, synthetic proteins and polypeptides, organic molecules, and the like. Present assembly proposals utilize chemical interactions and self-organization of molecules. Likewise, in optical fields the need for miniaturization requires the ability to fabricate optical devices having structures designed and built on the nanometer scale. The advantages afforded by such devices are already established theoretically, and it remains a challenge to create such devices with the beneficial properties predicted. A notable example of a pressing need for these materials is the data storage arena.
A formidable technical problem which remains unsolved is to devise a way to successfully position various different elements in a directed manner so as to produce devices, connect them to other components, such as electrodes, and integrate them into conventional systems. Important advances have been made using new lithographic techniques based on chemically controlled self assembly, microcontact printing, and self assembly in semiconductor film growth. Insofar as is known, however, it is not feasible to position individual nanometer sized device elements using these previously proposed approaches.